///
// * jdbm LICENSE v1.00
// *
// * Redistribution and use of this software and associated documentation
// * ("Software"), with or without modification, are permitted provided
// * that the following conditions are met:
// *
// * 1. Redistributions of source code must retain copyright
// *    statements and notices.  Redistributions must also contain a
// *    copy of this document.
// *
// * 2. Redistributions in binary form must reproduce the
// *    above copyright notice, this list of conditions and the
// *    following disclaimer in the documentation and/or other
// *    materials provided with the distribution.
// *
// * 3. The name "jdbm" must not be used to endorse or promote
// *    products derived from this Software without prior written
// *    permission of Cees de Groot.  For written permission,
// *    please contact cg@cdegroot.com.
// *
// * 4. Products derived from this Software may not be called "jdbm"
// *    nor may "jdbm" appear in their names without prior written
// *    permission of Cees de Groot. 
// *
// * 5. Due credit should be given to the jdbm Project
// *    (http://jdbm.sourceforge.net/).
// *
// * THIS SOFTWARE IS PROVIDED BY THE ndbm PROJECT AND CONTRIBUTORS
// * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
// * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
// * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
// * CEES DE GROOT OR ANY CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
// * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
// * OF THE POSSIBILITY OF SUCH DAMAGE.
// *
// * Copyright 2000 (C) Cees de Groot. All Rights Reserved.
// * Contributions are Copyright (C) 2000 by their associated contributors.
// *
// * $Id: RecordHeader.java,v 1.1 2000/05/06 00:00:31 boisvert Exp $
// 


//*************************************************************************
//**  Included in JDMB 1.0 port to SharpDBM;  11/2013 Cyrus Neah cneah@codingreal.com
//**  SharpDBM is an independent reimplementation of the JDBM 1.0 software library in C#  
//*************************************************************************


using SharpDBM.helper;

namespace SharpDBM.recman
{

///
// *  The data that comes at the start of a record of data. It stores 
// *  both the current size and the avaliable size for the record - the latter
// *  can be bigger than the former, which allows the record to grow without
// *  needing to be moved and which allows the system to put small records
// *  in larger free spots.
// 
	public class RecordHeader
	{
	// offsets
		private const short O_CURRENTSIZE = 0; // int currentSize
		private const short O_AVAILABLESIZE = Magic.SZ_INT; // int availableSize
		internal const int SIZE = O_AVAILABLESIZE + Magic.SZ_INT;

	// my block and the position within the block
		private BlockIo block;
		private short pos;

//    *
//     *  Constructs a record header from the indicated data starting at
//     *  the indicated position.
//     
		internal RecordHeader(BlockIo block, short pos)
		{
			this.block = block;
			this.pos = pos;
			if (pos > (RecordFile.BLOCK_SIZE - SIZE))
				throw new Error("Offset too large for record header (" + block.getBlockId() + ":" + pos + ")");
		}

	/// Returns the current size 
		internal virtual int getCurrentSize()
		{
			return block.readInt(pos + O_CURRENTSIZE);
		}

	/// Sets the current size 
		internal virtual void setCurrentSize(int @value)
		{
			block.writeInt(pos + O_CURRENTSIZE, @value);
		}

	/// Returns the available size 
		internal virtual int getAvailableSize()
		{
			return block.readInt(pos + O_AVAILABLESIZE);
		}

	/// Sets the available size 
		internal virtual void setAvailableSize(int @value)
		{
			block.writeInt(pos + O_AVAILABLESIZE, @value);
		}

	// overrides java.lang.Object
		public override string ToString()
		{
			return "RH(" + block.getBlockId() + ":" + pos + ", avl=" + getAvailableSize() + ", cur=" + getCurrentSize() + ")";
		}
	}

}